The present invention relates to a new acetylpolyamine amidohydrolase, to a process for producing the same, and to a method for quantitative determination of acetylpolyamine by using the same.
Polyamine is the generic name of putrescine, cadaverine, spermidine and spermine which are basic substances widely distributed in living bodies. Since Russel reported that the urine of cancer patients contains the polyamine in unusually large quantities (Cancer Res., 31, 1555, 1971), detection of polyamine has been applied to the diagnosis of cancer. Its quantitative determination is useful in the auxiliary cancer diagnosis and for the monitoring of the therapeutical effect of anticancer agents.
Electrophoresis, thin-layer chromatography (dansyl method), gas chromatography, high-performance liquid chromatography (HPLC) and analysis by means of an amino-acid analyzer have been used for the quantitative determination of the polyamine. However, in the quantitative determination of the polyamine contained in the urine, which exists for the most part in the form of acetyl derivative, the derivative must be hydrolyzed with hydrochloric acid into the corresponding free polyamine prior to analysis. This pretreatment is intricate in operation and detracts from the rapidity of analytical process. Enzymes capable of hydrolyzing acetylpolyamines (acetylpolyamine amidohydrolases), derived from Streptomyces avellanius (Japanese Published Unexamined Patent Application No. 144088/1981), Arthrobacter sp. (Japanese Published Unexamined Patent Application No. 43380/1985) and Micrococcus luteus (Japanese Published Unexamined Patent Application No. 98982/1985) have been known so far.
However, all the enzymes so far known are specific to acetylputrescine, and weak in acting upon other types of acetylpolyamine. Since the urine also contains acetylspermidine, acetylcadaverine and acetylspermine in significant quantities in addition to acetylputrescine, there has been a demand for a new type of enzyme which is capable of hydrolyzing these substrates with strong substrate affinity.
Intensive studies in search of a new acetylpolyamine amidohydrolase capable of acting upon many types of acetylpolyamines have led us to find that a microorganism belonging to the genus Mycoplana produces such an enzyme. The novel enzyme is different from known acetylpolyamine amidohydrolases in many properties, particularly in substrate specificity.